Sarah Conlon, the Belfast housewife who spent years campaigning to have the names of her husband Guiseppe and son Gerry cleared in one of the most high-profile miscarriage of justice cases in British legal history, has died aged 82 of lung cancer.

Gerry was one of the Guildford Four, jailed for life in 1975 for the IRA pub bombings at Guildford and Woolwich. Fourteen years, later, in 1989, his conviction was quashed and he was freed on appeal. His father, Guiseppe, was jailed for 12 years in 1976 after being swept up with the arrest of his sister-in-law Anne Maguire, having travelled to London to help prepare his son's defence. He died in prison in 1980, 11 years before he and the other members of the Maguire Seven had their convictions quashed. In 2005, the then prime minister Tony Blair issued a public apology to the families of those involved.

Sarah will be remembered as a woman of immense Catholic faith. She never gave up hope that one day the innocence of her husband and son would be proved. She retained huge reserves of fortitude and forgiveness, and she passed on the strength of her faith to Guiseppe and Gerry through regular letters and prison visits. A very private woman, she found within her the steely determination needed to take the spotlight and fight to clear the names of her loved ones. In the early days of the campaign - when many people in Belfast saw her as the mother of an IRA bomber - she stood virtually alone.

Born Sarah Maguire, she was one of seven siblings who lived with their parents Mary and Vincent in a small terrace house in Mary Street, just off the Falls Road, in the staunchly nationalist working-class west Belfast. She left school at 14 and took on a variety of jobs, including, like many working-class women of that time, working in the local linen mill. At the age of 21, she met Guiseppe Conlon, the love of her life, with whom she had three children, Gerard, Ann and Bridie. She later took a job as a catering assistant in the Royal Victoria hospital, Belfast. It was the wages from this job that - as a now single mother - she used to pay for trips to visit her husband and son in English jails.

Sarah's family was thrust into the world's media spotlight in 1974 with Gerry's wrongful arrest for the bombing of the Horse and Groom bar in Guildford, Surrey, in which five people died and 57 were injured, and the explosion at the nearby Seven Stars pub, where eight people were injured. Soon afterwards Paul Hill, Patrick Armstrong and his English girlfriend Carole Richardson were also arrested.

While a frail Guiseppe and his son served their sentences in England, back in Belfast Sarah took to lobbying dignitaries, church leaders and the media to secure their freedom. In the early years, she was very much a lone voice. But despite struggling to hold down a full-time job and bring up a family, she wrote to numerous Irish politicians, including the Social Democratic and Labour party MPs Joe Hendron and John Hume, to ask for their support. At one stage, she travelled to London to meet Cardinal Basil Hume to ask for his help. Her campaigning finally paid off in 1989 when the home secretary Douglas Hurd announced an inquiry into the Guildford bomb cases. Gerry's release, however, was no consolation for the loss of her husband in 1980. The father-of-three suffered from tuberculosis and emphysema for much of his life and struggled with his illnesses in prison. His family had just left him to travel back to Belfast when news reached them that he had died. That same day Sarah received a message from home secretary Willie Whitelaw stating that her husband was about to be released on compassionate grounds.

Fourteen years later, the injustice suffered by Sarah's family was made into a Hollywood movie In The Name of the Father, starring Daniel Day-Lewis. In the Jim Sheridan movie, which was nominated for an Oscar, Northern Ireland actor Marie Jones played Sarah.

Twenty-five years after her husband's death, Sarah and her family decided to fight for a public apology for the miscarriage of justice which had scarred her family. Once again, she led the campaign, lobbying church leaders and politicians, among them the Irish taoiseach Bertie Ahern, who pledged his support. She was unable to make the trip to London to hear the apology at first hand, but her children spoke to her by telephone from Blair's room in the Commons; as a reporter with the Irish News, I witnessed him reading the apology to Sarah's family. On hearing the news, she said she believed Guiseppe was "smiling down from heaven".

Sarah won huge admiration in Ireland for her quiet dignity and refusal to feel bitterness. She will be buried next to her husband in the Milltown cemetery on the Falls Road, west Belfast. Gerard, Ann and Bridie survive their mother.